I just wanted to finish up this thread, just in case anyone runs across this and needs a solution.
After looking here on the forum for answers and getting on the phone with Qnap support I found out this.
The most stable way to have your Roon core on a flash drive plugged into your NAS as an external drive is to plug the drive in and format it from the NAS. I no longer see this drive in my Mac Finder but it’s ability to talk to Roon and to the NAS works perfectly. I have had no problems what so ever in the last week.There are no issues playing any supported audio files. All Streaming radio works as well. If you run across a problem, post it here and I can walk you though my journey.
MAC
QNAP
EXTERNAL FLASH DRIVE (ROON CORE)